Drainage channels are known means for draining water from the surfaces of squares and public roads. Pre-fabricated conduits under the surface are cast in a concrete berm. Gratings made of shaped plates provided with slots or of cast iron are used as covers. It is customary to design the crowns of the side walls so that they can receive and retain these gratings. This can be accomplished either with a projecting rib made of the material or by means of a frame placed on the channels. The channel are now often made of polyester concrete.
It is known that the crowns of the side walls must be, for this reason, practically twice as thick as the lower part in order to give them the necessary strength.
In order to avoid using this additional material, which sharply increases the costs of the channels, German Patent 3 149 552 suggests mounting a metal frame on the channel walls and anchoring it therein. A further solution along these lines is described in German Registered Design (Utility Model) 84 35 101, which suggests using a shaped sheet-metal part instead of an expensive shaped strip with anchoring openings on both sides, which can be penetrated by the casting material. With this shaped part, the blank is folded around a fold line to form a double-layer side leg for lateral clamping of the gratings. One of the two layers forms the outer retaining leg, and the other forms the inner retaining leg after double folding. The two retaining legs are provided with anchoring clasps directed toward each other in order to form a rigid connection for the channels with the casting material.
Since this kind of edge protection is placed in the mold before casting of the channel, and the channel is removed after setting of the casting material, it is seen that shrinkage of the casting material and these rigid edge protection shapes can cause buckling of the channels, which cannot be used without reworking.
It is therefore an object of the invention to devise an edge protection for drainage channels, which will not cause any warping of the channels, but will result in a neat and satisfactory bearing and recess for the gratings in the pavement of the roadway or square.